The stated source: https://www.cdc.gov/mmwr/volumes/69/wr/mm6909e1.htm does not seem to have anything about 5% nationwide requiring ICU care although I've not checked the links within that. But it does seem a bit off.
The point is, if a health check fails or if there is an outage on AZ 2 then the ELB should be scripted to route to AZ 1 only, as well as AZ 3 if it exists.
It might sound condescending but I am merely stating facts and my opinon which froms the basis of my version of 'truth' as is the OP. I did not call anyone a liar at least.
Well, your system is not fault-tolerant if you have cross dependencies between AZs. I find their reporting accurate - AZ outage, not Regional as per your post.